I emailed DirecTV to ask this very question, as I indicated to them that if I order the game via the remote, it only shows up on the receiver from which I ordered it and not my other two receivers. If I call them to order the game, they not only do I have to wait FOREVER, they want to charge me $5 for calling.
I asked why couldn't there be an option to order via their TV listings online? They replied that since these games are added weekly, they often don't get them on the guide until the morning of the game, and adding an order option to the website would be too difficult.
Whatever. Sounds pretty lame, but I guess with DirecTV we must either go through the hassle and added expense of calling them, or be confined to one TV set by ordering from the remote.